There is a desire for thermoplastic polymers which are impregnated with fragrance. For example, there is a desire for thermoplastic polymers which have fragrances, such as, perfume, flower, and fruit. The major difficulty with making such thermoplastic polymers centers around how the polymer can be impregnated with sufficient fragrance material without adversely affecting either the polymer or the fragrance material.
With some polymers impregnating can be achieved by soaking the polymer in the fragrance material or a solution containing the fragrance material. Soaking suffers from various drawbacks. Many polymers, notably thermoplastic polymers, are difficult to impregnate in this manner because of the slow rate, even at elevated temperatures, at which the fragrance materials diffuse into the polymer. And where elevated temperatures are required, there is a limitation placed on the choice of the fragrance material. The fragrance material cannot be heat sensitive.
Thermoplastic polymers are typically impregnated by introducing the fragrance material into a polymer melt prior to compression or injection molding. However, the high temperatures of the polymer melt can volatilize, degrade or otherwise adversely affect the fragrance material. U.S. Pat. No. 3,926,655 discloses a perfumed polyamide resin which is made by heating the polyamide resin until it is pourable and stirrable then blending a perfume oil therein. Similarly, U.S. Pat. No. 4,095,031 discloses perfumed polymers of ethylene and polar monomer made by heating the polymer until it is free-flowing and then blending a perfumed oil therein.
Nippon Oil, in Japanese unexamined application No. 59 152-151-A, discloses a fragrant thermoplastic resin packaging bag made from a sheet of soft resin with perfume and thermoplastic resin.
Nippon Oil, in Japanese unexamined application No. 59,124,941, discloses copolymer impregnated with 17% perfume kneaded with polyethylene to give pellets releasing fragrance.
U.S. Pat. No. 4,167,589 discloses a process for producing caffeine-free black tea which includes an aroma impregnation step. The process comprises first extracting the aromatic ic content from the tea with a supercritical solvent, separating the aromatic content from the solvent by reducing the pressure and extracting caffeine from the tea residue with a moist supercritical solvent. The aromatic content is then redissolved in a supercritical gas which is subsequently liquified. The tea residue is impregnated with the aromatic content by drawing off the subcritical gas from the liquid phase in the presence of the tea residue. The role of the liquified gas is to function as a precipitation medium for the aroma.
A need exists to impregnate other materials, such as, pharmaceuticals and pest control agents, into polymers for controlled release. Langer, in Chem. Eng. Commun., Vol. 6, pages 1-48 (1980), discloses the application of polymeric delivery systems in pharmaceutical, agricultural and fragrance uses. Langer, et al., in Biomaterials 2, October, 201-214 (1981) discloses some medical control release applications.
Peyron, in Parfums, Cosmetiques, Aromes, No. 55, 47-54, February-March (1984), discusses extraction of fragrance and pharmaceutical materials from natural products using carbon dioxide. Sims, in U.S. Pat. No. 4,281,171 (July 28, 1981), discloses that pyrethrins, which are useful as pest control agents, can be extracted from pyrethrum flowers with liquid carbon dioxide. Stahl, in Rev. Latinoamer. Quim. 11, 1-7 (1980), discloses that some alkaloids dissolve at 40.degree. C. in supercritical carbon dioxide or nitrous oxide.
Grubb, U.S. Pat. No. 3,725,311; Wilbert, et al., U.S. Pat. No. 3,567,119; and Engel, U.S. Pat. No. 3,688,985 each discloses impregnated polymer systems.